Maleic Anhydride Grafted LLDPE Having High Melt Index

Abstract

Disclosed is a linear low-density polyethylene grafted with maleic anhydride (MAH-g-LLDPE). The MAH-g-LLDPE has a unique combination of properties including a low density and a high melt index.

We claim: 
     
         1 . A linear low-density polyethylene (LLDPE) grafted with maleic anhydride (MAH-g-LLDPE) in the absence of an added free radical initiator,
 wherein the MAH-g-LLDPE has a melt index (MI) of 250 to 800 g/10 minutes measured according to ASTM D1238, Condition 190/2.16,   wherein the MAH-g-LLDPE comprises 0.01 to 3 weight percent of maleic anhydride, based on the total weight of the MAH-g-LLDPE, and   wherein the LLDPE is a copolymer of ethylene and 1-hexene.   
     
     
         2 . The MAH-g-LLDPE according to  claim 1 , which comprises 0.1 to 2 weight percent of maleic anhydride. 
     
     
         3 . The MAH-g-LLDPE according to  claim 1 , wherein the LLDPE has a density of 0.890 to 0.925 g/cm 3  before grafting. 
     
     
         4 . The MAH-g-LLDPE according to  claim 1 , wherein the LLDPE has an MI of 0.1 to 10 g/10 minutes before grafting. 
     
     
         5 . The MAH-g-LLDPE according to  claim 1 , which has an MI of 300 to 800 g/10 minutes. 
     
     
         6 . A hot melt adhesive comprising:
 (a) the MAH-g-LLDPE according to  claim 1 ;   (b) a tackifier resin; and   (c) a wax.   
     
     
         7 . The hot melt adhesive according to  claim 6 , wherein the MAH-g-LLDPE comprises 0.1 to 2 weight percent of maleic anhydride. 
     
     
         8 . The hot melt adhesive according to  claim 6 , wherein the LLDPE has a density of 0.890 to 0.925 g/cm 3  before grafting. 
     
     
         9 . The hot melt adhesive according to  claim 6 , wherein the MAH-g-LLDPE has an MI of 300 to 800 g/10 minutes. 
     
     
         10 . The hot melt adhesive according to  claim 6 , which comprises from 30 to 60% by weight of the MAH-g-LLDPE, based on the total weight of the hot melt adhesive. 
     
     
         11 . The hot melt adhesive according to  claim 6 , which comprises from 5 to 15% by weight of the MAH-g-LLDPE, based on the total weight of the hot melt adhesive. 
     
     
         12 . The hot melt adhesive according to  claim 6 , which further comprises a base polymer comprising a metallocene-catalyzed polyethylene. 
     
     
         13 . A carpet backing comprising the MAH-g-LLDPE according to  claim 1 . 
     
     
         14 . A mixture of polymers, the mixture comprising a compatibilizer, wherein the compatibilizer comprises the MAH-g-LLDPE according to  claim 1 . 
     
     
         15 . A coating composition comprising the MAH-g-LLDPE according to  claim 1 , a dispersant, and optionally a pigment or a dye. 
     
     
         16 . A process for preparing a linear low-density polyethylene (LLDPE) grafted with maleic anhydride (MAH-g-LLDPE), the process comprising:
 (a) melting a LLDPE having a melt index (MI) of 0.1 to 10 g/10 minutes in an extruder to form a molten LLDPE;   (b) introducing maleic anhydride into the extruder; and   (c) contacting the molten LLDPE with the maleic anhydride in the extruder at conditions effective to increase the MI of the LLDPE and to form the MAH-g-LLDPE,   wherein step (c) is carried out in the absence of an added free radical initiator,   wherein the MAH-g-LLDPE has a MI of 250 to 800 g/10 minutes and comprises 0.01 to 3 weight percent of maleic anhydride, based on the weight of the MAH-g-LLDPE,   wherein the MI is measured according to ASTM D1238, Condition 190/2.16, and   wherein the LLDPE is a copolymer of ethylene and 1-hexene.   
     
     
         17 . The process according to  claim 16 , wherein the LLDPE has a density of 0.890 to 0.925 g/cm 3  before grafting. 
     
     
         18 . The process according to  claim 16 , wherein the extruder has a temperature profile ranging from 80 to 450° C. 
     
     
         19 . The process according to  claim 16 , wherein the LLDPE has an average residence time in the extruder of 1 to 5 minutes. 
     
     
         20 . The process according to  claim 16 , wherein the extruder has a screw speed of 300 to 600 revolutions per minute.